Project Summary. A key question in the study of stress-related psychiatric disorders concerns the temporal sequences and molecular mechanisms of long-term biological memories of stress exposure. In particular, which molecular changes translate into functional consequences relevant to psychiatric disorders often remains elusive. Prior evidence suggests a role for epigenetic modifications in response to stress exposure even across generations; however, many questions remain. We propose to leverage biological samples collected as part of an already funded longitudinal, developmental study in a non-human primate (NHP) model of early life stress (ELS) to examine the chronology and dynamics of maltreatment induced genome-wide modification of DNA methylation (DNAm) from birth to adolescence. The dynamic epigenetic changes will be correlated with relevant functional outcomes including stress-related neuroendocrine, behavioral and neurodevelopmental phenotypes. In addition, the fact that the study uses a cross-fostering experimental design with random group assignment at birth will allow us to answer the controversial question of whether infant maltreatment in NHP can lead to epigenetic modifications in subsequent generations, thus influencing stress- and trauma-related phenotypes in the offspring even without their own direct exposure to the trauma. Our goal is to examine the formation and function of DNAm patterns in response to ELS in NHPs and to investigate the effect of stress-elicited DNAm changes across generations. Our central hypotheses are that 1) ELS leads to age- and severity-dependent DNAm changes that are predictive of neuroendocrinological, neurodevelopmental and behavioral alterations, and 2) ELS in the parental generation will induce DNAm changes in stress-related genes in the subsequent generation implicating a biological inheritance of environmentally triggered epigenetic marks, which is supported by our preliminary data. We will test these two hypotheses through two specific aims: 1) Determine and compare DNAm profiles, and corresponding functional outcomes, longitudinally from birth through adolescence in NHPs exposed to ELS and matched controls. 2) Taking advantage of the unique cross-fostering experimental design, we will use information on ancestral maltreatment to investigate the interaction of ancestral and current maltreatment on DNAm profiles in offspring to determine the epigenetic and functional outcomes of infant maltreatment across generations. Our proposal's significance lays in the fact that these longitudinal, controlled studies on ELS and the investigation of intergenerational epigenetic effects of trauma exposure in humans are not feasible. Our NHP model offers a direct translational approach with the unique possibility to associate the epigenetic profiles with functional readouts across generations. The exploratory studies in this R21 application will lay the foundation for future studies as part of an R01 mechanism that will investigate 1) the molecular function of genes that are epigenetically modified by ELS in NHPs and 2) the molecular mechanism of intergenerational epigenetic effects of stress exposure.